Leukemia cutis is the infiltration of the skin by leukemic white blood cells, producing firm bumps, nodules, or plaques that are usually red, brown, or purple. It is uncommon, but it matters: it often signals that leukemia is active outside the bone marrow, and it can be the first sign of a new diagnosis or a relapse. Not every skin change in a person with leukemia is leukemia cutis, though. Many are caused by low blood counts, infections, or medications instead.
This overview explains what leukemia cutis is, how it differs from other skin manifestations of leukemia, how it is diagnosed, and what treatment involves.
What Is Leukemia Cutis?
Leukemia starts in the bone marrow, where blood cells are made. In most people, the abnormal cells stay in the marrow and bloodstream. In leukemia cutis, some of those cells leave the circulation and settle in the dermis, the deeper layer of the skin, where they build up into visible lesions.
It can occur with almost any type of leukemia, but it is most closely linked with acute myeloid leukemia (AML), especially subtypes where the cells resemble monocytes. It is also seen with chronic myelomonocytic leukemia, some T-cell leukemias, and occasionally chronic lymphocytic leukemia. It is rare in chronic-phase chronic myeloid leukemia.
Specific vs. Nonspecific Skin Manifestations
People with leukemia can develop many skin changes. Clinicians divide them into two groups: specific lesions, which contain leukemic cells, and nonspecific lesions, which are reactions to the disease or its treatment. Only the first group is leukemia cutis.
| Skin finding | Category | Underlying cause |
|---|---|---|
| Firm papules, nodules, plaques | Specific (leukemia cutis) | Leukemic cells in the dermis |
| Myeloid sarcoma (chloroma) | Specific | A tumor-like mass of myeloid blasts |
| Petechiae and bruising | Nonspecific | Low platelet count |
| Pale skin | Nonspecific | Anemia |
| Skin infections, fungal lesions | Nonspecific | Low neutrophil count or treatment-related immune suppression |
| Sweet syndrome (tender red plaques with fever) | Nonspecific | Inflammatory reaction linked to the disease or certain drugs |
| Drug rashes, hair loss | Nonspecific | Chemotherapy and supportive medications |
This distinction is why biopsy is so central. Two lesions can look almost identical, yet one means leukemic spread and the other a treatable reaction.
Causes and Underlying Mechanisms
Normal white blood cells travel into tissues all the time using adhesion molecules, which let them grip vessel walls, and chemokine receptors, which follow chemical signals. Leukemic cells can hijack this same system, and some carry “skin-homing” receptors that steer them into the dermis.
Features that make skin involvement more likely include:
- Monocytic or myelomonocytic features in the leukemic cells.
- A high white blood cell count at diagnosis.
- Certain cytogenetic abnormalities associated with tissue invasion.
- Previously damaged skin, such as scars or sites of past shingles.
Leukemia cutis is not contagious and is not caused by anything the patient did to their skin.
Signs and Symptoms
Lesions most often appear as papules (small raised bumps), nodules (deeper, larger lumps), or plaques (flat, raised patches). They tend to feel firm or rubbery and range from skin-colored to pink, red-brown, or violet. Most are painless and do not itch, although some are tender.
They commonly appear on the trunk, arms, legs, and face, and can be single or widespread. Some people with monocytic AML also develop swollen gums. In babies with congenital leukemia, bluish nodules across the skin can give a “blueberry muffin” appearance.
Timing varies. Leukemia cutis usually appears at the same time as the blood diagnosis or later, during progression or relapse. Rarely, it appears before the blood or marrow shows disease, called aleukemic leukemia cutis. Our article on early leukemia cutis looks at those first changes in detail.
Diagnosis and Testing Approaches
Diagnosing leukemia cutis starts with a skin biopsy, usually a punch biopsy deep enough to sample the dermis and fat. Under the microscope, the pathologist looks for sheets or rows of atypical, immature white cells between the collagen fibers.
Immunohistochemistry then identifies the cells. Markers such as CD45 confirm white blood cell origin, while myeloperoxidase, lysozyme, CD68, CD33, and CD117 point to a myeloid lineage. CD34 is helpful when positive but is often absent in monocytic leukemias, so a negative result does not rule the diagnosis out.
Because leukemia cutis reflects systemic disease, an accurate diagnosis of leukemia requires a full workup. The standard leukemia tests include:
- A complete blood count and a review of the blood smear.
- Bone marrow aspiration and biopsy with flow cytometry.
- Cytogenetic and molecular testing to classify risk and identify targetable mutations.
- Imaging if deeper extramedullary disease is suspected.
Treatment Options and Management Strategies
The treatment of leukemia cutis is the treatment of the underlying leukemia. Systemic chemotherapy is the backbone for most acute leukemias, and targeted drugs, immunotherapy, or allogeneic stem cell transplantation may be added depending on the subtype and genetic profile.
Skin lesions usually fade as the leukemia responds. For lesions that persist, bleed, or cause discomfort, localized radiotherapy is the main local option, and electron beam therapy can treat widespread skin disease in selected cases. Topical steroids may ease itch or inflammation but do not eliminate leukemic cells.
In my practice, any new skin lump in a patient in remission is biopsied promptly, because it can be the earliest sign of relapse.
When to See a Doctor
Contact your hematology team or doctor promptly if you notice:
- New firm, painless bumps or nodules that persist for more than a couple of weeks.
- Red, brown, or purple skin lumps together with fatigue, fevers, night sweats, or easy bruising.
- Any new skin lesion during or after leukemia treatment, particularly while in remission.
- Swollen or bleeding gums without an obvious dental cause.
Seek urgent care for skin changes accompanied by fever while your neutrophil count is low, since infection can progress quickly.
Frequently Asked Questions
Is leukemia cutis the same as a leukemia rash?
Not exactly. “Leukemia rash” is often used for petechiae or bruising caused by low platelets, which contain no leukemic cells. Leukemia cutis specifically means leukemic cells have entered the skin, which a biopsy confirms.
Does leukemia cutis mean the leukemia has spread?
It means the disease is present outside the bone marrow, which is called extramedullary involvement. In AML this is generally considered a sign of more aggressive disease. Overall outlook still depends on subtype, genetics, and response to treatment.
Can leukemia cutis be cured?
The skin lesions can disappear completely when the leukemia goes into remission. Whether the leukemia itself can be cured depends on its type and risk profile, as with any leukemia.
Who treats leukemia cutis, a dermatologist or a hematologist?
Usually both. A dermatologist often performs the biopsy and helps interpret the skin findings, while the hematologist or oncologist directs systemic treatment. Radiation oncologists join when local therapy is needed.
For background on related hematologic disorders, visit our leukemia guide.
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